Power-gating is a method used to reduce power consumption of electronics in which inactive circuits (or inactive portions of a circuit) are disconnected from the power supply. For example, when a mobile phone is on standby and awaiting calls, circuits associated with calls may be disconnected from power and/or ground rails using switches. Disconnecting or “powering down” circuits may reduce the current being dissipated through the circuit, minimize power consumption, and lead to improved battery lifespan. When a powered down circuit is required for an operation (e.g., a phone call is received), the circuit is re-connected to the power supply or “powered up.”
Circuits being operated with power-gating techniques, e.g., to power down or power up the circuits, may suffer from noise and current surges during a power transition. As instantaneous charge current passes through a switching device or voltage generators being activated, differences in power supply and demand cause current fluctuations and noise. Such noise may be associated to self-inductance of bonding wires, parasitic inductance of power rails, and/or dynamic impedances that affect the stability of the power source. Noise resulting from power-gating may have undesirable consequences in the operation of a circuit. For example, if the noise associated with a power transition is greater than the noise tolerance of a circuit, that circuit may erroneously latch an incorrect value and/or perform an unintended operation.